Our general aims have been to understand the mechanisms of immunological tolerance in specific lymphocytes. We will continue our efforts to characterize the growth and differentiation of specific B lymphocytes isolated from FL-gelatin dishes and cloned in agar. This method allows the growth of several distinct subsets of mouse B lymphocytes, the isolation of their progeny, and the subsequent stimulation of these colonies by specific antigen. Moreover, these cells can be exposed to tolerogen either before or during the cloning process. The effects of monoclonal reagents against distinct self surface markers (such as IgD, Ia, etc.) on these clonable B cells (CFU-B) will be determined. Moreover, we shall continue to study FL-specific B lymphocyte hybrids constructed from these hapten-specific B cells and established B cell lines. These procedures should allow the delineation of the molecular mechanisms of immune recognition by specific clones of identical B cells with particular emphasis on negative signals provided by tolerogen as well as positive signals from accessory cells plus antigen.